Color receiver



Dec..f9 E958 c. H. JONES 2,863,939

COLOR RECEIVER Filed Feb. 14, 1955 4 Sheetssheet 1 RNEY ` CharlesH.Jones.

4 sheets-sheet 2 c. H. JONES COLOR RECEIVER Fi g. 4

ColorSwichinc Period Frame Field ea. 9g K9 Filed Feb. 14. 1955 Dec. a,w58 l Filed Feb. 14, 1955 COLOR RECEIVER 4 sheets-sheet 3 C. H. JONESCOLOR RECEIVER Dec. 9, i958 4 Sheets-Sheet 4 Filed Feb. 14. 1955INSINIMIN l'. hln aux .un

Coton nncnrvnn Charles H. Jones, Churchill, Pa., assigner toWestinghouse Electric Corporation, East Pittsburgh, Pa., a corporationof Pennsylvania Application February 14, 1955, Serial No. 487,883

15 Claims. (Cl. 178-5.4)

This invention relates to color television receivers of the linesequential type, and has as an object to improve such receivers.

In line sequential receivers, the primary colors are assigned toindividual lines in the scanning pattern, and the color sequence isintroduced as successive lines are scanned. Prior receivers of this typehave been unsatisfactory because of objectionable color crawl andflicker.

This invention provides a color television receiver of the linesequential type in which the color switching is accomplished duringhorizontal retrace. A switching sequence is provided which reducesobjectionable color crawl and fiicker. The switching power required isrelatively small.

Another object of this invention is to reduce color crawl in televisionreceivers of the line sequential type.

Another objecto-f this inventionis to reduce the power required forcolor switching in color television receivers of the line sequentialtype.

This invention will now be described with reference to the drawings, ofwhich:

Figure 1 is a block diagram illustrating one embodiment of thisinvention;

Fig. 2 is a circuit schematic showing the circuit components used in thecolor signal gates of Fig. 1;

Figs. 3A to 3M are a plot of voltage wave forms;

Fig. 4 is a chart showing the color switching sequence; and

Fig. 5 is a block diagram illustrating another embodiment of thisinvention.

Throughout the drawings, like reference characters refer to likeelements in the various figures.

In a standard television receiver using interlaced scanning with ahorizontal line frequency of 15,750 cycles per second (C. P. S.), thefield rate is 60 C. P. S. and the frame rate is 30 C. P. S. Horizontalretrace occurs in a 10.2 microsecond interval following a horizontalsweep interval of 63.5 microseconds.

The receiver of Fig. l is such a standard receiver and includes a syncpulse generator which delivers a horizontal sync signal Vs, shown byFig. 3A, which initiates horizontal trace in the usual manner, and whichtriggers a flip-flop multivibrator 11 which supplies a signal V2L havingthe wave form shown by Fig. 3B, one of the two tube sections of themultivibrator 11 conducting for one horizontal sweep period, followed bythe other tube section conducting for three horizontal sweep periods.The signal Va is delayed for 95 microseconds by a delay line 12 toproduce a signal Vc illustrated by Fig. 3C, which in a gate 13 gates thesync signal Vs to produce a pulse Vg which occurs once for every foursync vsignals as illustrated by Fig. 3D. The pulse V 5 triggers aone-shot multivibrator 14 which delivers a signal Vb, one tube sectionof the multivibrator 14 conducting for one horizontal sweep periodfollowing the pulse Vg, and its other tube section then conducting forthree horizontal sweep periods as illustrated by Fig. 3E. The signal Vbis similar to Va ex- 2,863,939 Patented Dec. 9, 1958 cept that it isinverted and is delayed for a period equal to two horizontal sweepperiods.

The signals Vl and Vb are delivered to a matrix 15 to provide threeoutput signals Vd, Ve and Vf, in which: 5

where k is a constant `direct current Voltage of volts. The wave formsof Vd, Ve and Vf are illustrated by Figs. 3F, 3H and 3G, respectively.

It will be noted Vd has a 0 value during the first horizontal line andduring every second line thereafter; has 20 a +20 value during thesecond horizontal line and during every fourth line thereafter, and hasa -20 value during the fourth horizontal line and during every fourthline thereafter.

Voltage Ve has a -20 Value during the rst horizontal line and duringevery second line thereafter, has a 0 value during the second horizontalline and during every fourth line thereafter, and has a +20 value duringthe fourth horizontal line and during every fourth line thereafter.

Voltage Vf has a +20 value during the first horizontal line and duringevery second line thereafter; it has a -20 value during the secondhorizontal line and during every fourth line thereafter, and it has a 0value during the fourth horizontal line and during every fourth linethereafter.

The voltages Vd, Ve and Vf are supplied to a threeposition, single-poleswitch 16 which is rotated at 2O C. P. S. by a motor l? to provide aswitching rate of 60 C. P. S. corresponding to and synchronized with theeld rate. An electronic switching device may be employed in place of theswitch 16. The output signal V1, from `the switch 16 is amplified in anamplitier 1S which has an amplication factor of 20, and supplied to acolor control electrode or one set of deflection wires 21 of adeflection focus grid color tube 19. Another set of deflection wires 22is connected to a +5 kilovolt source, and a phosphor plate screen 23 isconnected to a +18 kilovolt source. A coupling capacitor 20 is connectedbetween the deflection wires 21 and the ampliiier 18, and a resistor 24is connected between the two sets of deflection Wires 21 and 22.

The deflection focus grid color tube 19, such as described in an articleentitled Compatible Color Picture Presentation with the Single GunTricolor Chromatron, by Gow and Dorr in the lanuary 1954 issue of thePro- 55 ceedings of the l. R. E., has a phosphor screen with a largenumber of ne, equally spaced, parallel lines, one line iluoresces in redwhen impacted by the electron beam of the tube, another line liuorescesin green when irnpacted by the electron beam, and another line uorescesin blue when impacted by the electron beam. When +400 volts is appliedto the deflection wires of the tube, the electron beam is deflectedagainst the red phosphor line, when 0 voltage is applied to thedeflection wires, there is no deflection and the electron beam strikesthe green phosphor line, and when 400 volts is applied to the deflectionwires, the electron beam will be deflected against'the blue phosphorline. The +20, -20 and 0 voltages Vh delivered by the switch 16 to theamplifier 18 will be amplified to +400, -400 and 0 voltage requencewhich will be described later'.

The voltages V1, are also applied to the gates 25, 26 and 27 to whichthe blue, green and red color signals respectively from the receiver arealso applied.

The outputs of the three gates 25, 26 and 2'/ are added in an adder 28and supplied to a control grid of the tube 19. The details of the gates2S, 26 and 27 are shown in Fig. 2. The gates contain similar inputtransformers having primary windings 30 and center tapped secondarywindings 31, the center taps of which are connected to the switch 16 toreceive the gating voltage V1? The gate 25 has the resistors 32 and 33connected between the ends of its secondary winding 3l and its outputconnections 3ft. The two diodes 35' and 36 are connected in series,back-to-bacli. to the output connections. The junction connection of thediode-.3 and 36 is connected to a -10 volt direct current source. Whenthe gating signal Vh is 20 volts. the gate will pass a blue signal.

The gate 26 has a similar resistor 37. and a similar resistor 33connected between the ends of its secondary winding 3l to its outputconnections 37, und has the diodes 38 and 39 connected in series,baclt-to-baclt to the output connections 37. The junction connection ofthe diodes Sti and 39 is connected to a -l-lO volt direct currentsource. The oppositely poled diodes 'lfl and il are also connected inseries. baciato-haelt. to the output connections 37, and their junctionconnection is connectcd to a -l0 volt direct current source. When thegating signal V1, is at 0 volt, the gate 26 will pass a green signal.

The gate 27 has the resistors 32 and 3.a connected bctween the ends ofits secondary windings 31 and its output connections -l-Z, and has thediodes f3 and nlffl connected in series, bacli-to-back, to the outputconnections 42. The junction connection of the diodes and til is con--nected to a -l0 volt direct current sour When the gating signal V1, is+20 volts, the gate 2.7 will pass a red signal.

Assume before the start of the first horizontal line of the first field,thc color is to be switched to green. fore the first sync pulse startshorizontal trace, the voltage Vd will be 0 as illustrated by Fig. 3F.Assuming the rotor of the switch 16 touches the forward edge of theswitch sector 46 at this time. to which sector the voltage Vd isdelivered from the matrix 15. then the switch 16 will deliver a voltageVdr-O to the amplifier 1f? and through the amplifier to the deflectionwires of the color tube 19. At the same time, the 0 voltage gatingsignal '\f gates the gate 26 to pass the green color signal. Theelectron beam in the color tube strikes the green phosphor line at thesame tinte the green color signal is applied to the grid of the colortube. This repeated e lry second horizontal line following the firstwhen V51-0 illustrated by Fig. 3F. the rotor of the switch .16 remainingon the switch sector Af6 during the first held.

Before the start of the second line (the third line of the pattern shownin Fig. 1.1). and before the sync pulses Vs start horizontal trace. thevoltage WQ, will be +20 as shown by Fig. 3F. The rotor of the switch 16wi still bc on tbe sector 46 so that +20 volts will be oe- ]ivcred tothe amplifier 13 where it will be amplified to +400 volts and applied tothe deflection wires of the tube 19 at the same time that V1, gates thcgate 27 to par-:s the red color signals. Thus, the electron beam in thecolor tube strikes the red phosphor line at the same time the red colorsignal is applied to the grid of the color tube. This is repeated everyfourth horizontal line following the second (every eighth line followingthe third line of the pattern as shown in Fig. 4) when Vd=l20 asillustrated by Fig. 3F.

Before the start of the fourth line (the seventh line of the patternshown in Fig. 4) and before the sync pulses start horizontal trace, thevoltage VE, will be 20 as shown by Fig. 3F. The rotor of the switch 16will still be on the sector -fso that -20 volts will `be delivered tothe amplifier 18 where it will be amplified to -400 volts and applied tothe deflection wires of the tube 19 at the same time that V1, gates thegate 25. The electron beam in the color tube strikes the blue phosphorline at the same time the blue color signal is applied to the grid ofthe color tube. This is repeated every fourth horizontal line followingthe fourth (every eighth line following the seventh line of the patternas shown in Fig. 4) when Vd=-20 as illustrated by Fig. 3F.

Thus, during the first field, the color will be switched duringhorizontal retrace from green to red, to green, to blue, to green, tored, to green. to blue. and so on as shown by Fig. 4.

At the start of the second field, the rotor of the switch le will touchthe forward edge of the switch sector 47 which receives the voltage Vffrom the matrix 15. The sync signal VS, at the beginning of the firsthorizontal line of the second field (the second horizontal line of thepattern) and every second line thereafter will start horizontal trace.Before this time, the voltage V, will be -l-20 as illustrated by Fig. 3Gwhich will be amplifled by the amplifier 18 to +400 volts and applied tothe deflection wires of the tube 19. The gating voltage V gates the gate27 to pass the red color signal so that the red color signal will beapplied to the control grid of the color tube 19 at the same time theelectron beam in the tube is deflected against the red phosphor line.

Before the start of the second horizontal line of the second field (thefourth horizontal line of the pattern) and every fourth line thereafter,V, is -20 volts as shown by Fig. 3G. The rotor of the switch 16 willremain on the switch sector 47 during the second field so that -20 voltswill be supplied by the switch 16, amplified to 400 volts by theamplifier 18 and applied to the dcllection wires of the tube 19. Thegating voltage V gates the gate 2S to pass the blue color signal. Theblue color signal thus will be applied to the grid of the color tube atthe same time its electron beam is deflected against the blue phosphorline.

Before the start of the fourth line of the second field (the eighth lineof the pattern) and every fourth line thereafter, the voltage V, will be0 as shown by Fig. 3G. The rotor of the switch 16 will still be on thesector 47 so that 0 volt will be delivered through the amplifier 18 tothe deflection wires of the tube 19. The 0 voltage gating signal V1,will gate the gate 26. The green color signal thus will be applied tothe grid of the color tube at the same time its electron beam strikesthe green phosphor line.

Thus, during the second field, the color will be switched from red toblue, to red, to green, to red, to blue, to red, to green, and so on asshown by Fig. 4.

Before the beginning of the first horizontal line of the third field andevery second line thereafter, the voltage VC will be -20 as illustratedby Fig. 3H. At thc start of the third field, the rotor of the switch 16will touch the forward edge of the switch sector 48 which receives thevoltage Vc from the matrix 1S. The rotor of the switch 16 will remain inContact with the switch sector 48 throughout the third field. The switch16 will supply '20 volts to the amplifier 18 which will increase thisvoltage to -400 volts and the amplifier 13 will supply the lattervoltage to the deflection wires of the tube 19. At the same time thegating signal V of -20 voltsl will gate the gate 25 to pass the bluecolor signal so that it will be applied to the grid of the color tube 19at the same time the electron beam is deflected against thcI bluephosphor line. This will be repeated every second line following the rstline of the third field when the voltage Ve is -20 as illustrated byFig. 3H.

Before the beginning of the second horizontal line of the third fieldand every fourth line thereafter, V is 0 as shown by Fig. 3H. The switch1 6 will deliver a 0 voltage to the amplifier 18 so that 0 volt will besupplied to the deflection wires of the color tube 19. At the sassaresesame time the switch 16 will deliver a 0 gating voltage to the gate 26to pass the green color signal. The green color signal will thus beapplied to the grid of the tube 19 at the same time the electron beamstrikes the green phosphor line.

Before the start of the fourth horizontal line of the third field andevery fourth line thereafter, Ve is +20 as shown by Fig. 3H. The switch16 will deliver a +20 voltage to the amplifier 18 which will increasethis voltage to +400 volts and the amplifier 18 will supply the lattervoltage to the defiection wires of the tube 19. At the same time thegating signal Vh of +20 volts will gate the gate 27 to pass the redcolor signal. The red color signal will thus be applied to the grid ofthe tube 115 at the same time the electron beam strikes the red phosphorline.

Thus during the third field the signal will be switched from blue togreen, to blue, to red, to blue, to green, to blue, to red, and so on asshown by Fig. 4.

Before the start of the first line of the fourth field (the second lineof the pattern) and every second line thereafter, Vd is zero as shown byFig. 3F. The rotor of the switch 16 will again be touching the forwardedge of the switch sector 46 to which Vd is supplied by the matrix 15.The switch 16 will deliver a 0 voltage to the amplifier 13 so that 0volt will be supplied to the deflection wires of the color tube 19. Atthe Sametime the switch 16 will deliver a gating voltage of 0 volt tothe gate 27' to pass the green color signal. The green color signal willthus be applied to the grid of the tube 19 at the same time the electronbeam strikes the green phosphor line.

Before the start of the second line of the fourth field (the fourth lineof the pattern) and every fourth line thereafter, Vd is +20 as shown byFig. 3F. The switch 16 will deliver a +20 voltage to the amplifier 18which will increase the Voltage to +400 volts and the amplifier 18 willsupply the latter voltage to the deflection wires of the tube 19. At thesame time the gating signal Vh of +20 volts will gate the gate 28 topass the red color signal. The red color signal will thus be applied tothe grid of the tube 19 at the same time the electron beam strikes thered phosphor line.

Before the start of the fourth line of the fourth field (the eighth lineof the pattern) and every fourth line thereafter, Vd is +20 as shown byFig. 3F. The switch 16 will deliver a +20 voltage to the amplifier 18which will increase the voltage to -400 volts and the amplifier 13 willsupply the latter voltage to the defiection wires of the tube 19. At thesame time the gating signal Vh of -20 volts will gate the gate 25 topass the blue color signal so that it will be supplied to the grid ofthe color tube 19 at the same time the electron beam is defiectedagainst the blue phosphor line.

Thus during the fourth field the signal will be switched from green tored, to green, to blue, to green, to red, to green, to blue, and so onas shown by Fig. 4.

Before the beginning of the first line of the fth field and every secondline thereafter, the voltage Vf will be +20 as shown by Fig. 3G. Theswitch 16 will deliver a +20 voltage to the amplifier 18 which willincrease the voltage to +400 volts and the amplifier 18 will supply thelatter voltage to the defiection wires of the tube 19. At the same timethe gating signal Vh of +20 volts will gate the gate 2S to pass the redcolor signal. The red color signal will thus be applied to the grid ofthe tube 19 at the same time the electron beam strikes the red phosphorline.

Before the beginning of the second line of the fifth field and everyfourth line thereafter, Vf is -20 as shown by Fig. 3G. The switch 16will deliver a -20 voltage to the amplifier 1S which will increase thevoltage to -400 volts i d the amplifier 18 will supply the lattervoltage to the d lection wires of the tube 19. At the same time 6 thegating signal Vh of 20 Volts will gate the gate 25' to pass the bluecolor signal so that `itwill be supplied to the grid of the color tube19 at'thesametime as the electron beam is deflected against the bluephosphor line.

Before the start of the fourth line of the fth field and every fourthline thereafter, Vf is 0 as shown by Fig. 3G. The switch 16 will delivera 0 voltage to the amplifier 18 so that 0volt will be supplied to thedeflection wires of the c olor tube 19. At the same time the switch 16will deliver a 0 gating voltage to the gate 27 to pass the greencolorsignal. The green color signal will thus be applied to the grid of thetubet19 at the same time the electron beam strikes the green phosphorline.

Thus during the fifth yfield the signal will be switched from red toblue, to red, to green, to red, to blue, to red, to green, and so on asshown by Fig. 4.

Before the start of the first line of the sixth field (the second lineof the pattern) and every second line thereafter, the voltage Ve will be-20 as shown by Fig. 3H. The switch 16 lwilldeliver a -20 voltage to theamplifier 1S which will increase the voltage to -400 volts and theamplifier 18 will supply the latter voltage to the defiection wires ofthe tube 19. At the same time the gating signal Vh of -20 volts willgate the gate 25 to pass the blue color signal so that'it will besupplied to the grid of the color tube 19 at the same time as theelectron beam is deflected against the blue phosphor line.

Before the start of the second line of the sixth eld (the fourth line ofthe pattern) and every fourth line thereafter, V,3 is 0 as shown by Fig.3H. The switch 16 will deliver a 0 Voltage to the amplifier 18 so that 0volt will be supplied to the deflection wires of the color tube 19. Atthe same time the switch 16 will deliver a 0 gating voltage to the gate27 to pass the green color signal. The green color signal will thus beapplied to the grid of the tube 19 at the same time the electron beamstrikes the green phosphor line.

Before the start of the fourth line of the sixth field (the eighth lineof the pattern) and every fourth line thereafter, Ve is +20 as shown'byFig. 3H. The switch 16' will deliver a +20 voltage to the amplifier 18which will increase the voltage to +400 volts and the amplifier 18 willsupply the latter Voltage to the deflection wires of the tube 19. At thesame time the gating signal Vn of +20 volts will gate the gate 28 topass the red color signal. The red color signal will thus be applied tothe grid of the tube 19 at the same time the electron beam strikes thered phosphor line. 4

Thus during the sixth field the signal will be switched from blue togreen, to blue, to red, to blue, to green, to blue, to red, and so on asshown by Fig. 4.

This completes the first color switching period. There A is a similarperiod between the seventh and twelfth fields,

and between the thirteenth and eighteenth fields, and so on. It will benoted that after every sixth f1eld, every line in a picture has beenpresented in all three primary colors.

The switching sequence eliminates noticeable color crawl. Actually,there is upward crawl between odd and even fields, and downward crawlbetween even and odd fields, but the net effect is that visible crawl iscancelled out.

In order to reduce flicker it may be desirable to reduce the gain in thegreen channel by a factor of two during fields when the number of greenlines is twice the nurnber of blue and red lines, and similarly toreduce the gain in the red and blue channels by a factor of two duringfields when the number of red and blue lines is twice the number ofgreen and blue and red and green lines respectively. This could beaccomplished by providing a three sector switch similar to the switch 16and rotating in synchronism with it. The outputs of the three sectors ofthis additional switching means would feed red, green and blueamplifiers which may be located in the red, green and blue color signalchannels respectively. These outputs would control the respective gainsof the amplifiers. The input to the rotor of such a switch may besupplied from a convenient direct current source. In like manner and fora similar purpose, a switching means similar to the switch means of Fig.5 may be utilized in that embodiment of this invention.

The high frequency brightness information may be fed to the cathode oftube 19, or added to the three color signals either before or aftergating.

Although this invention has been described in Fig. l with reference to adeliection focus grid type color tube, it will be obvious that theswitching sequence is applicable to any tube in which colors can bedisplayed in a line sequential fashion. For example, the tube which isthe subject matter of Figs. l and 2 of the copending application of A.P. Krupcr and myself, Serial No. 411,382, led February 19, 1954, may usethis form of line sequential presentation.

Referring to Fig. 5, in detail, the numeral Gti designates the colortube referred to in the above copending appli` cation. The signals Vaand Vb are derived in a manner similar to that described with referenceto Fig. l and are delivered to a matrix 61 to provide three outputsignals VX. Vy and Vx, in which:

The wave forms of VX, Vy and VZ are illustrated by Figs. 3J. 3L and 3Mrespectively.

The voltages VX, Vy and V,I are supplied to switch sectors 63, Gd and 65respectively of a three-position, threepole switch cli ich is rotated at20 C. S. by a motor (i6. the switch 62 has three rotors ti7, 63 and 69.The rotor 67 is connected to a green gate 7tlg the rotor 63 is connectedto a blue gate 7l; and the rotor 69 is conneeted to a red gate 72. Thegates 7d, 71 and 72 are identical. and may be similar to the gate 27 ofFigs. l and 2. ill/hen no voltage is applied to these gates they will beclosed and when a positive 20 volts is applied to them they will openand thus allow the video color signal to pass to the adder 28.

The color-'tube 6G has a color control grid structure 73 comprisingthree sets of perforated conducting strips 74, 75 and 76 which arepositioned adjacent to a phosphor screen 77. The screen 77 comprises aplurality of green. blue and red phosphor stripes. The conducting strips74 hich are positioned opposite thc green phosphor stripes ure allconnected together by a conductor 78 and are connected on the outside ofthe tube tothe rotor 67. 'lhe conducting strips '75 which are positionedopposite the blue phosphor stripes are all connected together by theconductor 79 and are connected on the outside ofthe tube to the rotortiti. rthe conducting strips 76 which are positioned opposite the redphosphor stripes are all connected together by the conductor 30 and areconnected on the outside ot` the tube to the rotor 69. The tube achievesn lens action by applying proper voltages to the conductive coating tt?.and to the unipotential grid struc ture 83. The cathode of the tube isat a slight positive potential so that with zero voltage applied to theconductors 75l. 7l) and Sd. electrons will not pass through the colorcontrol grid '7.3 to the phosphor screen 77.

Assume before the start of the iirst horizontal line of the first field.the color is to be switched to green. The lirst sync pulse will starthorizontal trace. At the same time the voltage VA.; will be +20, asillustrated by Fig. 3J. Assuming the rotor 67 of the switch tif. touchesthe forward edge otj the :mitch sector 63 at this time, to which sectorthe voltage Vx is delivered from the matrix 6l, then the switch 67. willdeliver a 'voltage Vz-t-ZO to the conductor 73 of the tube Gti. At thesame time. the gating signal Vm=-l 2O will gate the gate 70 to pass thcgreen color signal. At the same time the voltage Vy will be 0. asillustrated by Fig. 3L. The rotor 69 will touch the forward edge of thesector 64, to which sector the voltage Vy is delivered from the matrix,6l, and the switch 62 will deliver a voltage l/IO to the conductor titland to the gate 72. At the same time the voltage V7 will he l), asillustrated by Fig. 3h' The rotor 63 will touch the forward edge ot thesector 65, to which sector the voltage V,. is delivered from the matrix6l. and the switch 62 will deliver a voltage l/:ztl to the conductor 79and to the gate 7l. The voltages Vy and VZ will not gate the gates "i2and "/'i respectively and since the cathode ol the tube (zt) is at aslight positive voltage, electrons will not pass through the colorcontrol grid 73 to the blue and red phosphor stripes on the screen 77.The electron beam will strike the green phosphor stripe at the same timethe green color signal is applied to the grid of the color tube.

From the preceding description, it is apparent trom an examination ofFigs. 3]. 3L and 3M that the saine switching sequence described indetail with reference to Fig. l can be accomplished in the Fig. 5embodiment of this invention.

While I have shown my invention in preferred embodiments, it will beobvious to those skilled in the art that it is not so limited, but issusceptible of various changes and modilications without departing fromthe spirit thereof.

l claim as my invention:

l. A color television receiver having horizontal and vertical sync pulsegenerators for providing pulses for sychronizing horizontal and verticalsweeps comprising: a color tube of the line sequential type having a control electrode, a cathode. a phosphor screen having primary colorphosphor lines, and means for controlling the passage of the electronbeam from said cathode to said phosphor lines; a plurality of gatesconnected to said control electrode; means for applying primary colorsignals to said gates; means including means initiated by sync pulsesfrom said horizontal generator for generating a plurality of voltages insynchoronisni with said generator, and means including switching meansoperable at the field rate of said receiver for applying said voltagesto said gates and to said control means to thereby provide a linesequential display in which the number of phosphor lines or" aparticular primary color impinged by the clcctron beam during apredetermined field is equal to tl e number of phosphor lines of theother primary colors im pinged by the electron beam during saidpredetermined field, and phosphor lines of a different particularprimary color are impinged by the electron beam in successive fields.

2. A color television receiver as claimed in claim l in which means isprovided lor increasing the voltages before they are applied to thecontrol means.

3. A color television receiver having horizontal and Vertical sync pulsesources for providing pulses for synchronizing horizontal and verticalsweeps comprising: a color tube of the line sequential type and having acontrol electrode, a cathode, a phosphor screen having primary colorphosphor lines. and means for controlling the passage ot. the electronbeam from said cathode to said lines; a plurality of gates connected tos'eid control clectrode; means for applying primary color signals tosaid gates; means including means initiated by n sync pulse from saidhorizontal source for providing a hrst voltage in phase with said pulseand having a duration equal to one horizontal sweep period. and forproviding a second voltage which starts two horizontal sweep periodsafter the start ol said hrst voltage, which has a duration equal to onehorizontal sweep period, and which has a polarity opposite to that ofsaid lirst voltage; matricing means using said voltages for producingthree voltages in synchronism with the frequency of said horizontalsource, and means including switching means operable at the held rate ofsaid receiver for applying said three voltages to said gates and to saidcontrol means to thereby provide a line sequential display in which thenumber of phosphor lines of a particular primary color impinged 'by theelectron beam during a predetermined field is equal to the number ofphosphor lines of the other primary colors impinged by the electron beamduring said predetermined field, and phosphor lines of a differentparticular primary color are impinged by the electron beam in successivefields.

4. A color television receiver as claimed in claim 3 in which means isprovided for increasing the three voltages before they are applied tothe control means.

5. A color television receiver having horizontal and vertical sync pulsegenerators for providing pulses for synchronizing horizontal andvertical sweeps comprising:

a color tube `of the line sequential type and having acontrol electrode,a cathode, a phosphor screen having primary color phosphor lines, andmeans for controlling the passage of the electron beam from said cathodeto said lines; a plurality of gates connected to said control electrode;means for applying primary color signals to said gates; means includingmeans initiated by a sync pulse from said horizontal generator forproviding a first voltage in phase with said pulse and for providinganother voltage after said irst voltage and having a polarity oppositeto the polarity of the `iirst voltage; means using said voltages forproducing three voltages in synchronism with said horizontal generator,and means including switching means operable at the field frequency ofsaid receiver for applying said three voltages to said gates and to saidcontrol means to thereby provide a line sequential display in which thenumber of phosphor lines of a particular primary color impinged by theelectron beam during a predetermined field is equal to the number ofphosphor lines of the other primary colors impinged by the electron beamduring said predetermined field, and phosphor lines of a differentparticular primary color are impinged by the electron beam in successivefields.

6. A color television receiver as claimed in claim 5 in which means isprovided between said switching means and said control means foramplifying said three voltages.

7. A color television receiver having horizontal and vertical sync pulsegenerators for providing pulses for synchronizing horizontal andvertical sweeps comprising: a color tube of the line sequential typehaving a rst and a second control electrode; a plurality of gatesconnected to said first control electrode; means for applying primarycolor signals to said gates; means including means initiated by syncpulses from said horizontal generator for generating a plurality ofvoltages in synchronism with said horizontal generator; and meansincluding switching means operable at the eld rate of said receiver forapplying said voltages to said gates and to said second controlelectrode to thereby provide a line sequential display in which thenumber of phosphor lines of a particular primary color impinged by theelectron beam during a predetermined iield is equal to the number ofphosphor lines of the other primary colors impinged by the electron beamduring said predetermined eld, and phosphor lines of a differentparticular primary color are impinged by the electron beam in successiveelds.

8. A color television receiver as claimed in claim 7 in which means isprovided between the switching means and the second control electrodefor amplifying the voltages applied to said second control electrode.

9. A color television receiver as claimed in claim 7 in which thevoltages have periods equal to four horizontal sweep periods.

l0. A color television receiver as claimed in claim 3 in which the threevoltages have periods equal to four horizontal sweep periods.

ll. A color television receiver as claimed in claim 5 in which the threevoltages have periods equal to four horizontal sweep periods.

12. A color television receiver as claimed in claim 7 in which the meansfor generating a plurality of voltages includes means for generating twovoltages having periods equal to four horizontal sweep periods andhaving opposite polarities, one of said tw-o voltages starting two sweepperiods after the other of the two voltages, and in which means usingthe two voltages generates the said plurality of voltages.

13. A color television receiver as claimed in claim l2 in which theplurality of voltages have periods equal to four horizontal sweepperiods.

14. A color television receiver having horizontal and vertical syncpulse generators for providing pulses for synchronizing horizontal andvertical sweeps comprising: a color tube having a first and a secondcontrol electrode; a plurality of gates connected to said rst controlelectrode, means for applying primary col-or signals to said gates;means including means initiated by a sync pulse from said generator forproviding a rst voltage coincident with and in phase with said pulse,said voltage having a positive value for one horizontal sweep periodfollowed by a zero value for three horizontal sweep periods, andfollowed by a second positive value for one horizontal sweep period,said means initiated by said sync pulse providing a second voltagesimilar to said first voltage but out of phase therewith and startingtwo horizontal sweep periods after the start of said rst voltage;matricing means using said voltages for producing three voltages insynchronism with said horizotnal generator; means including switchingmeans operable at the iield rate of said receiver for applying saidthree voltages to said gates, and means connecting said switching meansto said second control electrode to thereby provide a line sequentialdisplay in which the number of phosphor lines of a particular primarycolor impinged by the electron beam during a predetermined field isequal to the number of phosphor lines of the other primary colorsimpinged by the electron beam during said predetermined held, andphosphor lines of a diiterent particular primary color are impinged bythe electron beam in successive iields.

15. A color television receiver as claimed in claim 14 in which themeans connecting the switching means and the second control electrodeincludes means for amplifying the three voltages.

References Cited in the ile of this patent UNITED STATES PATENTS2,650,264 Weirner ---a Aug. 25, 1953 2,704,783 Sziklai Mar. 22, 19552,705,257 Lawrence Mar. 29, 1955 2,744,952 Lawrence May 8, 19562,759,992 Kindred Aug. 21, 1956 2,759,993 Loughlin Aug. 21, 1956

